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V (No Model.)

J B DAVIDS I MEANS FOR PROMOTING COMBUSTION IN FURNACES.

No. 530,299. Patented Dec; 4, 1894.

' Nrrnn STATES PATENT OFFICE.

JOHN B. DAVIDS, OF NORTH DARTMOUTH, MASSACHUSETTS, ASSIGNOR TO E. M. OHISHOLM DAVIDS, OF SAME PLACE.

MEANS FOR PROMOTING CO MBUSTION IN FURNACES.

SPECIFICATION forming part of Letters Patent No. 530,299, dated December 4, 1894.

Application filed April 19, 1894. Serial ll'o. 508,090. (No model.)

To all whom it may concern:

Be it known that 1, JOHN B. DAVIDS, a citizen of the United States, residing at North Dartmouth, in the countyof Bristol and State of Massachusetts, have invented certain new and useful Improvements in Means for Promoting Combustion in Furnaces, of which the following is a specification, reference being had to the accompanying drawings, in Which-- I Figure 1, is a view inberpendicularsection of a portion of a smoke stack, fitted with my improvement. Fig. 2, is a top View of a smoke stack, provided with my improvements, and Fig. 3, is an elevation of a smokestack, provided withmy improvements.

Similar letters of reference indicate like parts in the several views.

The object of my invention is to provide improved means for increasing the draft in furnaces, and it consists in introducing air under pressure, into the smoke stack, through a series of tubes, whose orifices open into said stack at varying heights from its base, and arranged in such a manner that the blast from the shortest tube, will be assisted or accelerated by that from the next longer tube,

' and the blast from that, by the next, and so on throughout the series.

b, represents the smoke stack, and a, repre sents an air tight, annular chamber, surrounding the base of the same.

01, d, represent a series of tubes, having their bottom ends secured in the wall of the chamber a, and extending upward to varying heights, with their orifices opening intothe interior of the stack. These tubes are pref erably arranged as shown, commencing with the shortest, and constantly increasing in length, until the full circle of the stack is completed. The tops 6, of these tubes, are preferably inclined slightly inward, and also in the direction of their increasing length, in order that the blast from the shortest tube may be .taken up and accelerated by the blast from the next longer, and that, by the xext longer, and so on throughout the series, giving a whirling motion to the column of air within the stack, which greatly assists the upward draft.

h, represents a pipe, provided with a valve, connecting the annular chamber a, with a reservoir containing air under pressure.

In Figs. 1, and 2, the tubes d, cl, are represented as extending upward, inside of the smoke stack; in which case, the partition 0, which serves to distribute the air from the pipe h, equally to all the tubes d d, is secured to the bottom of the chamber and extends nearly to the top of the same.

In Fig. 3, the tubes d, d, are represented as being secured in the top of the chamber a, and extending upward,outside of the smoke stack to the desired height, and then entering the same, as shown by the dotted lines. Inthis case, the partition in the chamber a, is horizontal and extends inward, from the outside wall of said chamber.

When it is desired to increase the draft in the stack and thereby promotethecombustion of the fuel in the furnace, the valve in the pipe h, is opened, and the compressed air allowed to flow into the chamber a, and through the tubes 61, d, into the stack. As the cool air issues in a blast from the tubes, it is at once expanded by the hot air from below, and rushes with accelerated speed from the top of the stack,thus causing a partial vacuum below, which the air under the fire box, rushes'through the fire to fill,and thereby promotes the rapid combustion of the fuel, and increases the effective force of the fire.

Having thus described my invention, what I claim, and desire to secure by Letters Patent, is-- I 1. In combination with a smoke stack, having a chamber surrounding its base, a series of tubes connecting said chamber with the interior of said stack and extending upward, their tops terminating in a helical line, and inclining slightly toward the center of the stack and in the direction of their increasing length; and means for forcing air through said tubes, all as shown and for the purpose described.

2. In combination with a smoke stack, a series of tubes extending upwardfrom a point near the base of said stack, their tops terminating in a helical line, and opening into said stack; and means for forcing air through said tubes, all asshown and for the purpose described.

JOHN B. DAVIDS. Witnesses: v

HENRY W. MASON, Limits 0. HITCH. 

